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| interface ComputerPartVisitor {
void visit(Computer computer);
void visit(Mouse mouse);
void visit(Keyboard keyboard);
void visit(Monitor monitor);
}
interface ComputerPart {
void accept(ComputerPartVisitor computerPartVisitor);
}
class Keyboard implements ComputerPart {
@Override
public void accept(ComputerPartVisitor computerPartVisitor) {
computerPartVisitor.visit(this);
}
}
class Monitor implements ComputerPart {
@Override
public void accept(ComputerPartVisitor computerPartVisitor) {
computerPartVisitor.visit(this);
}
}
class Mouse implements ComputerPart {
@Override
public void accept(ComputerPartVisitor computerPartVisitor) {
computerPartVisitor.visit(this);
}
}
class Computer implements ComputerPart {
ComputerPart[] parts;
public Computer() {
parts = new ComputerPart[]{new Mouse(), new Keyboard(), new Monitor()};
}
@Override
public void accept(ComputerPartVisitor computerPartVisitor) {
for (ComputerPart part : parts) {
part.accept(computerPartVisitor);
}
computerPartVisitor.visit(this);
}
}
class ComputerPartDisplayVisitor implements ComputerPartVisitor {
@Override
public void visit(Computer computer) {
System.out.println("Displaying Computer.");
}
@Override
public void visit(Mouse mouse) {
System.out.println("Displaying Mouse.");
}
@Override
public void visit(Keyboard keyboard) {
System.out.println("Displaying Keyboard.");
}
@Override
public void visit(Monitor monitor) {
System.out.println("Displaying Monitor.");
}
}
public class VisitorPatternDemo {
public static void main(String[] args) {
ComputerPart computer = new Computer();
computer.accept(new ComputerPartDisplayVisitor());
}
}
|